Neuropathology

Question 1

This question is about cerebrospinal fluid.

How much is normal?
Where is it produced and reabsorbed?
What is its metabolic importance?
Where is it circulated?

Answer 1

Normal volume 150ml

Produced by choroid plexus in the lateral ventricles (500ml every 24 hours)

Reabsorbed by arachnoid granulations in the subarachnoid space

Metabolic importance:

1. Cushioning of the CNS
2. Role in immune regulation and defence
3. Cerebral autoregulation

Circulated through the lateral ventricles –> interventricular formamen–> third ventricle –> cerebral aqueduct –> fourth ventricle –> central canal

Question 2

Define and explain the causes of hydrocephalus

Answer 2

A condition in which there is an accumulation of CSF in the brain. (Very rarely OVERproduction)

• COMMUNICATING: aka non-obstructive hydrocephalus, is caused by impaired cerebrospinal fluid reabsorption in the absence of any CSF-flow obstruction between the ventricles and subarachnoid space
• NON COMMUNICATING: there is a physical block
• Very rarelt due to overproduction of CSF

!Leads to shrinking of brain tissue (as in dementia)= ex vacuo
-If it occurs before fusion of cranial sutures it causes enlargement of the head circumference

Question 3

What is considered raised intracranial pressure?

Causes?

Answer 3

Means CSF pressure > 200mm H2O

Causes:

• Increased CSF volume (hydrocephalus)
• Intracranial space occupying lesion (neoplasm, haemorrhage, abscess)
• Cerebral oedema (can be vasogenic-increased vascular permeability or cytotoxic- neuronal, glial or endothelial cell damage)

Question 4

What are the types of herniation?

Answer 4

Subfalcial (cingulate)
Central/transtentorial
Tonsillar/cerebellar - can cause compression of the medulla with impairment of vital respiratory and cardiac functions

Question 5

Which kind of haemorrhages may be classified as space-occupying lesions?

What other space occupying lesions are there?

Answer 5

Extradural/epidural haemorrhage
Subdural haemorrhage
Subarachnoid haemorrhage
Intracerebral haemorrhage

Ischaemic infarct (stroke) with subsequent oedema or haemorrhage
Neoplasm
Abscess

Question 6

What kinds of head trauma can occur?

Answer 6

Skull fracture
Vascular injury
Coup injury (injury on side of impact)
Contrecoup injury (injury on opposite side of impact)
Parenchymal injury e.g. contusion (bruising), laceration (penetration or tearing), diffuse axonal injury

Question 7

Consider vascular injury

What kind of injury is most likely to cause an extradural hemorrhage?

Which vessel is most likely to be ruptured?

Symptoms?

CT appearance?

Answer 7

Severe trauma with arterial laceration

Middle meningeal artery (following break of temporal bone, particularly pterion)

Often there is loss of consciousness following a head injury, a brief regaining of consciousness, and then loss of consciousness again. Other symptoms may include headache, confusion, vomiting, and an inability to move parts of the body. Complications may include seizures

Biconvex appearance (semi circle)

Question 8

Consider vascular injury

What kind of injury is most likely to cause a subdural hemorrhage?

Which vessel is most likely to be ruptured?

Symptoms?

CT apperance?

Answer 8

Trauma may be minor in atrophy

Bridging veins which cross the subdural space

Slower onset, gradually increasing headache and confusion

Crescent appearance

Question 9

Consider vascular injury

What kind of injury is most likely to cause a subarachnoid hemorrhage?

Which vessel is most likely to be ruptured?

Symptoms?

CT appearance?

Answer 9

Rupture of saccular (berry) aneurysm

Circle of Willis

Severe headache of rapid onset, vomiting, decreased level of consciousness, fever, and sometimes seizures and neck stiffness

Fluid in ventricles

Question 10

Consider vascular injury

What is an intraparenchymal haemorrhage?

What kind of injury is most likely to cause an intraparenchymal hemorrhage?

Answer 10

A type of intracerebral bleed. It is within the actual brain tissue. The other type is intraventricular.

Hypertension

Question 11

State the distribution of berry aneurysms on circle of Willis?

Answer 11

40% on anterior communicating artery
20% on posterior communicating artery
34% middle cerebral artery
4% basilar artery

Question 12

How much of the hearts CO and O2 is relayed to the brain?

What kinds of stroke are there?

Answer 12

15% of CO and 20% of O2 demand (neurons are the most oxygen sensitive cells)

In a stroke there is a SUDDEN onset of neurological symptoms

Can be hypoxia or ischaemia (global vs focal)

Haemorrhagic infarction in emboli (petechial lesions e.g. BM)
Ischaemic infarction in thrombosis

Question 13

What is typical of the histology of stroke?

Answer 13

Ren neurons
Pyknosis of nucleus
Shrinkage of the cell body
Loss of nucleoli
Intense eosinophilia of cytoplasm

**Owing to irreversible hypoxic/ischaemic insult

Question 14

Are neoplasms likely to be primary or metastatic?
How frequent are they in children?
Where do they originate?

Answer 14

75% are primary, the rest metastatic

20% of malignant childhood tumours are located in the CNS

Gliomas (astrocytoma, oligodendroglioma, glioblastoma)
Neural tumours (ganglion cell tumours)
Meningiomas
Poorly differentiated neoplasms (medullablastoma)
Primary CNS lymphoma
Metastasis (lung, breast, skin/melanoma, kidney, GI tract)
Peripheral nerve tumours (schwanoma, neurofibroma, MPNST)

Question 15

What are the commonest causes of meningitis in:

New borns
Children
University students
Adults/The elderly

Immunocompromised?

Other?

Answer 15

Newborns: Group B Streptococcus, Strept. pneumoniae, Listeria monocytogenes, E.coli

Babies and children: Strept. pneumoniae, Neisseria meningitidis, Haemophilus influenzae type b (Hib), group B Streptococcus

Teens and young adults: Neisseria meningitidis, Strept. pneumoniae

Older adults: Streptpneumoniae, Neisseria meningitidis, Haemophilus influenzae type b (Hib), group B Streptococcus, Listeria monocytogenes

Immunocompromised: viral menigitis (HIV, enterovirus`), Candida fungus, parasites (toxicoycisis from pets)

RMSV, Neurosyphilis, lyme disease, malaria

Question 16

What are the commonest causes of abscess. encephalitis and localised infections?

Answer 16

Abscess- usually bacterial

Encephalitis- viral (HSV, CMV, HIV, JC polyoma virus)

Localised- toxoplamosis, cysticerosis

Question 17

Consider the progressive/degenerative conditions.

Give an example for a:

1. Neurodegenerative disease
2. Spinocerebellar degenerative disease
3. Demyelinating disease
4. Prion disease
5. Genetic metabolic disease
6. Toxic and acquired metabolic disease

Answer 17

1. Alzheimers, Parkinsons
2. Dementia
3. Multiple sclerosis
4. Creudzfeldt-Jakob
5. Neuronal storage disease
6. Vitamin B1 & B2 deficiency, CO toxicity, alcohol toxicity, radiation toxicity

Question 18

How may a tonsilar hernia present?

Answer 18

Tonsiliar herniation compresses oculomotor nerve

Leads to blown pupil

Question 19

What is a berry aneursym?

Acute complications of burst aneurysm?
Treatment options?

Answer 19

A blood vessel with a weakened tunica intima.
Vasoplasm leading to subsequent ischaemia
Coiling, clipping

Question 20

Whos at an increased risk of an intracerebral hemorrhage?

Answer 20

Older than 60
Systemic coagulopathy
Liver failure
post-surgical stasis
Cancer/neoplasm
Vasculitis
Amyloid (occurs around any vessel)

Question 21

What would you see in a slipped disc?

How does this contrast to an infective lesion (abscess) on the spinal cord? Symptoms?

Answer 21

Non-destructive lesion on spinal cord

Structure of vertebrae either side is maintained

No smell

Destructive lesion, vertebrae either side would be affected and there would be a smell
-Causes falls

Question 22

State 3 causes of focal weakening of bone

Answer 22

Cancer metastasis
Osteoporosis (more common in women)
Myeloma (too many plasma cells, classic pepper box appearance on xray, where bone isnt, myeloma is)

Question 23

How would a teenager likely present with Meningitis?

What sign might the patient show at clinical examination?

Differential diagnosis?

Answer 23

Fever
Cold hands/feet
Acute-onset headache associated with irritability, confusion and vomiting
Photophobia
Purpuric non-blanching rash (caused by vasculitis caused by the meningitis)
Neck stiffness

Cant do a straight leg raise form sitting position (meninges travel down with spinal cord)

Drug reaction? Lupus? Vasculitis?

Question 24

State 3 risk factors for meningitis

Answer 24

SUPPRESSED IMMUNE SYSTEMS

• Alcoholism
• HIV/AIDS
• Cancer
• Diabetes
• IV drug users
• Spleenectomy
• Smokers

Skull trauma
Cerebral shunt
Cochlear implant

Question 25

Which investigations would you perform to confirm the diagnosis of meningitis?

Answer 25

If suspected meningitis, give antibiotics straight away

Lumbar puncture after checking no raised intracranial pressure (test via CT)
-Causes Coning (brainstem herniation through foramen magnum- Tonsillar herniation)

Question 26

What would the pathology look like in meningitis?

Answer 26

Brain covered in pus
Exudate on base of skull
Loss of gyri due to inflammation

Question 27

What types of intracerebral tumours are there? How do they differ?

Why does it kill (type 1)?

How to treat?

Answer 27

Meningioma - 2/3 occur in women (can occur spontaneously in pregnancy), generally benign, well circumscribed, arises from the choroid plexus
Meningisarcoma - infiltritive

Presses on medulla causing raised intracranial pressure

External beam radiation to try and shrink/stop growth
Excision